Microphone system



Sept 11, 1928. 1,684,053

1 G. E. BLIZIOTIS MICROPHONE SYSTEM Filed Jan. 22, 1924 WITNESSES: INVENTOR Geo/7e E. 5/12/0 Us" My BY ATTORNEY Patented Sept. 11, 1928.

UNITED STATES 1,684,053 PATENT OFFICE GEORGE E. BLIZIOTIS, OF NEWARK, NEW JERSEY, ASSIGNOR TO WESTINGHOUSE ELEC- TRIO & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

MICROPHONE SYSTEM.

Application filed January 22, 1924. Serial No. 687,727.

My invention relates to microphonic sound-responsive systems.

One object of my invention is to produce a, system wherein a plurality of micophones may be operated in parallel.

Another object of my invention is to produce a microphone system comprising adjusting means for securing similar operating characteristics of a plurality of m1crophones.

Another object of my invention is to provide means whereby several microphones may be operated in parallel to respond to the same sound sources.

Another object of my invention is to provide a plurality of potentiometer current adjusting means in combination with a plurality of microphones whereby the operating characteristics of the microphones are severally adjusted to produce similar soundresponse characteristics.

Still another object of my invention is to provide a plurality ofpotentiometer current adjusting means in combination with a plurality of microphones whereby the operating characteristics of the microphones are severally adjusted in accordance with the quality of the sound to which they are desired to respond.

In the prior art of construction of microphone systems for response'to sound by which vibratory electric currents corresponding to the vibrations comprising the sound waves are produced, it has been customary to use a single microphone to respond to all of the sound which it is desired to copy into the vibratory electric currents. Even for such purposes as obtaining a sound pick-up for radio broadcastin it has been customary to use, at one time, only a single microphone for the sound response.

Difiicnlty has, however, been experienced in obtaining a satisfactory responsev by a single microphone in instances where it has been necessary to copy sounds from several sources simultaneously. Under these conditions, the nearest sound sources most strongly influenced the microphone, while the more remote sound sources produced a proportionately less response. This condition tended to result in a copy of the sound in electric currents which was unbalanced and which, when retranslated into sound at some remote point, was not a satisfactory copy of theisounds which an auditor would have heard directly from the sources.

It is therefore found desirable to use a plurality of microphones variously placed with respect to the plurality of sound sources so that, when one-microphone responds fully to sound from certain sources, another microphone will respond fully to other of the sound sources.

Vhen attempts were first made to operate microphones connected in parallel, it was found to be impracticable to do so by an ordinary system of parallel connections. The difficulty experienced was found to be caused by dissimilarity in the response characteristics and resistance of the various microphones.

My invention provides a regulating and adjusting system whereby more than one microphone can be connected to a given output line and operated in parallel to produce a sound translation of the several sources desired simultaneously.

Other objects and structural details of my invention will be apparent from the following description when read in connection with the accompanying drawings, wherein:

The single figure is a diagrammatic sketch of the circuits and devices required for my invention.

Referring to the drawing, 'L'WO double button microphones 1 and 2 are supplied by a source of electric current 3 through potentiometers 4 and 5 and milliameters 6 and 7. The microphones are also connected, as indicated, to the primary windings of transformer 8 having two primaries t) and 11 and a secondary 12.

The secondary 12 is further connected to an amplifier system 13 which supplies current to a transmission line 14 by which the vibratory electric currents representing the soundare conveyed to a remote point which may be, as indicated, a radio broadcasting system 15.

In the operation of my device, the presence of potentiometers 4 and 5 permits the currents through microphones 1 and 2 to be independently adjusted, by which means the response characteristics of the microphones to a given sound are also capable of adjustment.

One microphone is placed in a suitable relation to the group of sound sources whereby it will be selectively responsive to the desired portion of the sound. sources. The magnitude-of this response to those-sound sources is then controlled by the potenti ometer and, consequently, the magn tude of the vibratory electric currents" transmitted from it through the Winding of the transformer. By this means, a suitable ick up may be obtained from a portion 0 the group of sound sources.

Another microphone'is placed in suitable relation to the group of sound sources to be predominately responsive to another portion of the group. Its degree of response is then controlled by its potentiometer to give the necessary amplitude to vibratory electric currents which it sends through the trans: former. The milliameters indicated enable the operator to estimate the relative degree of response of their respective microphones to the chosen sound sources, thereby enabling the operator to determine the respective degree of responseof the micro bones -to the sound sources which it is desired to By this means, I have produced a system comprising a plurality of microphones whose characteristic operating qualities and whose degree of response are separately under the control of the operator, whereb he is enabled to employ a plurality of ,m1cr o phones for the reception and translation of sound from a single group of sound sources and whereby he is further enabled, when so desired, to accentuate the response to sound from certain portions of the group of sound sources.

While I have shown only one embodiment of my invention in the accompanying drawings, it is capable of various changes and modifications without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be imposed in the appended claims.

I claim asmy invention: v

1. In combination, a plurality of diifen ential microphones cumulatively connected to a translating device, a voltage source have ing a terminal thereof connected to said translating device, resistors connected shunt to said voltage source, and a variable connection from an intermediate electrode of each of said microphones to one of said resistors, whereby the response characteristics of said microphones maybeadjusted. v 2. In combination, a plurality of differential microphones cumulatively connected to a translating device, a voltage source having a terminal thereof connected to anintermediate point on said translating device, resistors connected in shunt to said, voltage source, and a variable connection from an electrode of each of said microphones to one of said resistors, whereby the voltage across said microphones may be independently adjusted.

3. In combination, a plurality of dilierv ential microphones of the double button type cumulatively connected to a translat- G. E. BLIZIOTIS. 

